central venous pressure and intra-arterial blood pressure monitoring. invasive intraoperative monitoring

central venous pressure and intra-arterial blood pressure monitoring. various sites for cvp and Ibp insertion. working principle for cvp and ibp. indication and complication. various waveform of cvp and ibp

1. CVP AND IBP BY:- DR. PRATEEK GUPTA 2 ND YEAR PG (ANESTHESIA

2. CVP P ressure measured in the central veins close to the heart. It indicates mean right atrial pressure and is frequently used as an estimate of right ventricular preload. CVP reflects the amount of blood returning to the heart and the ability of the heart to pump the blood into the arterial system. It is the pressure measured at the junction of the superior vena cava and the right atrium. CVP monitoring helps to assess cardiac function, to evaluate venous return to the heart, and to indirectly gauge how well the heart is pumping.

3. It reflects the driving force for filling of the right atrium & ventricle.  It indicates the relationship of blood volume to the capacity of the venous system. Normal CVP in an awake , spontaneously breathing patient : 1-7 mmHg or 5-10 cm H2O. Mechanical ventilation : 3-5 cm H2O higher Single value has no value. Trend is important.

4. In terms of pressure 1cm H 2 O = 0.73 mmHg. 1 mmHg = 1.36 cm H 2 O.

5. Indication Major operative procedures involving large fluid shifts or blood loss Intravascular volume assessment when urine output is not reliable or unavailable Temporary Hemodialysis Surgical procedures with a high risk for air embolism, CVP catheter may be used to aspirate intracardiac air Frequent venous blood sampling, Inadequate peripheral intravenous access Temporary pacing Venous access for vasoactive or irritating drugs & Chronic drug administration Rapid infusion of intravenous fluids (using large cannulae) Total parenteral nutrition

6. Factors A f fecting CVP Cardiac Function Blood Volume Capacitance of vessel Intrathoracic & Intraperitoneal pressure 1 /0 2 /2 18

7. Common Insertion Site Internal Jugular Subclavian Femoral External Jugular Basilic Axillary 1 /0 2 /2 18

8. 1 /0 2 /2 18 Right IJV is Preferred Consistent , predictable anatomy Alignment with RA Palpable landmark and high success rate No thoracic duct injury

9. CENTRAL VENOUS PRESSURE MONITORING In central venous pressure monitoring, the physician inserts a catheter through a vein and advances it until its tip lies in or near the right atrium. Because no major valves lie at the junction of the vena cava and right atrium, pressure at end diastole reflects back to the catheter.

10. W A VEFORM

11. 1 /0 2 /2 18 Mechanical Events Waveform Component Phase of Cardiac Cycle Mechanical Events ‘a’ wave End Diastole Atrial Contraction(after P wave) ‘c’ wave Early Systole Isovolumic right ventricle contraction, TV bow in RA(after QRS) ‘x’ descent Mid Systole Atrial Relaxation, Descent of RV base(TV annulus) ‘v’ wave Late Systole Filing of RA with venous blood(just after T wave) ‘y’ descent Early Diastole Early ventricular filling, opening of TV ‘h’ wave Mid to Late Diastole Diastole plateau

12. ‘a’ wave Atrial Contraction(after P wave) End Diastole Prominent a wave: resistance in RV filling- RVH, TS, T a mponade , PS, Pulmonary hypertension Absent a wave: Atrial fibrillation or flutter Cannon A waves occur as the RA contracts against a closed TV: junctional rhythm, CHB,ventricular arrhythmias 1 /0 2 /2 18

13. ‘c’ wave Isovolumic right ventricle contraction, TV bow in RA(after QRS) Early Systole TR: Tall Systolic c-v wave It is call holosystolic cannon v waves 1 /0 2 /2 18

14. ‘x’ descent Atrial Relaxation, Descent of RV base(TV annulus) Mid Systole Dominant x descent –good RV function and vice versa Cardiac Tamponade - X descent is steep & Y descent is diminished 1 /0 2 /2 18

15. ‘v’ wave Filing of RA with venous blood(just after T wave ) Late Systole Prominent v wave with increase venous return. ASD, PAPVC or TAPVC, A-V malformation Large V waves may also appear later in systole if the ventricle becomes noncompliant because of ischemia or RV failure. Decrease in RA emptying. TS 1 /0 2 /2 18

16. ‘y’ descent Early ventricular filling, opening of TV Early Diastole Attentuation of y descent: TS, Tachycardia, RVF, Tamponade,PS 1 /0 2 /2 18

17. 1 /0 2 /2 18 Measurement The phlebostatic axis is the reference point for zeroing the hemodynamic monitoring device. 4th intercostal space, mid-axillary line 1 mmHg = 1.36 cm H2O. the first step in pressure transducer setup is to zero the transducer by exposing it to atmospheric pressure Thus, a cardiac filling pressure of 10 mm Hg is 10 mm Hg higher than ambient atmospheric pressure.

18. Respiratory Effect A, During spontaneous ventilation, the onset of inspiration ( arrows ) causes a reduction in intrathoracic pressure, which is transmitted to both the CVP and pulmonary artery pressure (PAP) waveforms. CVP should be recorded at end-expiration. B, During positive-pressure ventilation, the onset of inspiration ( arrows ) causes an increase in intrathoracic pressure. CVP is still recorded at end-expiration. 1 /0 2 /2 18

19. 1 /0 2 /2 18 Fluid Responsiveness: inspiratory fall of CVP > 1 mmHg is high predictive of fluid responders Keeping CVP > 5 mmHg in renal transplant surgery is associated with good graft function In first 3 post op days Post cardiac surgery CVP > 15 mmHg is associated with poor outcome

20. 1 /0 2 /2 18 Decrease in CVP is relatively late sign of depletion of intravascular volume CVP is better measurement of volume status in anesthetised patient whose autonomic reflexes are abolished Goal directed fluid therapy has not shown good results in critically ill patients .

21. Location – under the medial border of lateral head of SCM. Right IJV preferred – leads straight to SVC and RA – minimises injury to thoracic duct, pneumothorax. Position : Supine with head down position Head turned to opposite side IJV APPROACH

22. IJV APPROACH

23. IJV APPROACH

24. IJV APPROACH

25. IJV APPROACH

26. USG guided – advantages : Minimises injury to carotid artery Helps to identify the anatomy Especially advantageous in patients with difficult neck anatomy, prior neck surgeries and anticoagulated patients. IJV APPROACH

27. Tortuous path – reduced success rate Advantages – avoids advancement of needle into deeper structures. EJV APPROACH

28. Supraclavicular and infraclavicular approach High incidence of complications – esp pneumothorax. Site of choice in patients undergoing surgeries of head and neck and in trauma patients immobilised with cervical collar Useful in parentral nutrition/prolonged CVP monitoring SUBCLAVIAN VEIN

29. Advantage – Decreased complications Ease of access Disadvantage – Difficult to ensure correct central venous placement of cathether. Car di ac perforation and arrythmias ANTECUBITAL VEINS

30. ABSOLUTE SVC syndrome – CI to upper extremity placement Infection at the site of insertion RELATIVE Coagulopathies Newly inserted pacemaker wires CONTRAINDICATIONS- CENTRAL VENOUS CANNULATION

31. COMPLICATIONS OF CENTRAL VENOUS CANNULATION Arterial puncture with hematoma A-V fistula Hemothorax, chylothorax, pneumothorax Brachial plexus injury Horner’s syndrome Air embolism Catheter/wire shearing COMPLICATIONS

32. COMPLICATIONS OF CATHETHER PRESENCE Thrombosis/thromboembolism Infection, sepsis, thromboembolism Arrythmias Hydrothorax COMPLICATIONS

33. INTRA ARTERIAL BLOOD PRESSURE Intra-arterial blood pressure (IBP) measurement is often considered to be the gold standard of blood pressure measurement . It involves the insertion of a catheter into a suitable artery and then displaying the measured pressure wave on a monitor .

34. INDICATIONS: 1 . Continuous, real-time blood pressure monitoring 2 . Planned pharmacologic or mechanical cardiovascular manipulation 3 . Repeated blood sampling 4 . Failure of indirect arterial blood pressure measurement 5 . Supplementary diagnostic information from the arterial waveform 6 . Determination of volume responsiveness from systolic pressure or pulse pressure variation

35. close monitoring of critically ill patients on vasoactive drugs

36. COMPLICATIONS Distal ischemia, pseudoaneurysm, arteriovenous fistula Hemorrhage , hematoma Arterial embolization Local infection, sepsis Peripheral neuropathy Misinterpretation of data Misuse of equipment

37. ADVANTAGES Reduces the risk of tissue injury and neuropraxias in patients who will require prolonged blood pressure measurement M ore accurate than NIBP, especially in the extremely hypotensive or the patient with arrhythmias.

38. COMPONENTS OF AN IABP MEASURING SYSTEM : Intra-arterial Cannula Fluid Filling tube Transducer In f usio n /Flushi n g system Signal processor, amplifier and display

39. COMPONENTS OF AN IABP MEASURING SYSTEM Wheatstone bridge diagphragm Strain gauge Signal processor, amplifier and display

40. Intra-arterial cannula Should be wide and short Forward flowing blood contains kinetic energy When flowing blood is suddenly stopped by tip of catheter, kinetic energy is partially converted into pressure. This may add 2-10mmHg to SBP This is referred to as end hole artifact or end pressure product. Cannulation sites: Radial, Ulnar, Dorsalis Pedis , Posterior tibial , Femoral arteries

41. Fluid filled tubing Provides a column of non-compressible, bubble free fluid between the arterial blood and the pressure transducer for hydraulic coupling. Ideally , the tubing should be short, wide and non-compliant (stiff) to reduce damping . extra 3-way taps and unnecessary lengths of tubing should be avoided where possible

42. Transducer Converts mechanical impulse of a pressure wave into an electrical signal through movement of a displaceable sensing diaphragm. It functions on principle of strain gauze and wheatstone bridge circuit .

43. Wheatstone bridge Circuit designed to measure unknown electrical resistance Rx = R2/R1 * R3

44. Strain Gauze Are based on the principle that the electrical resistance of wire or silicone increases with increasing stretch. The flexible diagram is attached to wire or silicone strain gauges in such a way that with movement of the diaphragm the gauges are stretched or compressed, altering their resistance

45. Infusion/flushing system Fills the pressure tubing with fluid and helps prevent blood from clotting in catheter, by continuously flushing fluid through the system at a rate of 1-3ml/ hr , - by keeping a flush bag at pressure of 300mmHg. Heparinizing the flush system is not necessary

46. Signal processor, amplifier and display The pressure transducer relays its electrical signal via a cable to a microprocessor where it is filtered, amplified, analyzed and displayed on a screen as a waveform of pressure vs. time. Beat to beat blood pressure can be seen and further analysis of the pressure waveform can be made, either clinically, looking at the characteristic shape of the waveform, or with more complex systems, using the shape of the waveform to calculate cardiac output and other cardiovascular parameters

47. COMPONENTS OF AN IABP MEASURING SYSTEM Wheatstone bridge diagphragm Strain gauge Signal processor, amplifier and display

48. Invasive Blood Pressure Monitoring Transducer Zeroing : For accurate reading, atmospheric pressure must be discounted from the pressure measurement Transducer Levelling : level with the patient’s heart, at the 4th intercostal space, in the mid-axillary line.

49. COMPONENTS OF AN IBP MEASURING SYSTEM 26-07-2016 Dr. Vikram Naidu 59

50. Levelling and zeroing Zeroing : For a pressure transducer to read accurately, atmospheric pressure must be discounted from the pressure measurement. This is done by exposing the transducer to atmospheric pressure and calibrating the pressure reading to zero. The level of the transducer is not important. 60

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52. Levelling : The pressure transducer must be set at the appropriate level in relation to the patient in order to measure blood pressure correctly. This is usually taken to be level with the patient’s heart, at the 4th intercostal space, in the mid-axillary line. A transducer too low over reads, a transducer too high under reads. 26-07-2016 Dr. Vikram Naidu 62

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54. The normal waveform for an invasive ABP Initial sharp rise (left ventricular systole Rounded slope represents the peak systolic pressure Dicrotic notch: represents the closure of the aortic valve Descending slope signifies the beginning of diastole .

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56. As the pressure wave travels from the central aorta to the periphery , the arterial upstroke becomes steeper, the systolic peak increases, the dicrotic notch appears later, the diastolic wave becomes more prominent, and end-diastolic pressure decreases. 26-07-2016 Dr. Vikram Naidu 66

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58. Invasive Blood Pressure Monitoring PHYSICAL PRINCIPLES Sine Waves : Amplitude Frequency Wavelength Phase

59. FUNDAMENTAL FREQUENCY The arterial pressure wave consists of a fundamental wave (the pulse rate) and a series of harmonic waves . - These are smaller waves whose frequencies are multiples of the fundamental frequency The process of analyzing a complex waveform in terms of its constituent sine waves ( Fourier Analysis )

60. Invasive Blood Pressure Monitoring T he complex waveform is broken down by a microprocessor into its component sine waves, then reconstructed from the fundamental and eight or more harmonic waves of higher frequency to give an accurate representation of the original waveform . The IABP system must be able to transmit and detect the high frequency components of the arterial waveform (at least 24Hz) in order to represent the arterial pressure wave precisely . This is important to remember when considering the natural frequency of the system

61. The arterial pressure wave has a characteristic periodicity termed the fundamental frequency, which is equal to the pulse rate. Although the pulse rate is reported in beats per minute, fundamental frequency is reported in cycles per second or hertz (Hz ). If the heart rate is 60 beats/min, then this equals one cycle per second ( 1 Hz) So the fundamental frequency is 1 Hz.

62. Accuracy of IABP Monitoring : Natural Frequency and Resonance : quantifies how rapidly the system oscillates Damping Coefficient: quantifies the frictional forces that act on the system and determine how rapidly it comes to rest. Transducer Zeroing and Levelling

63. Natural Frequency & Resonance Every material has a frequency at which it oscillates freely. This is called its natural frequency . If a force with a similar frequency to the natural frequency is applied to a system, it will begin to oscillate at its maximum amplitude. This phenomenon is known as resonance.

64. Invasive Blood Pressure Monitoring If the natural frequency of an IABP measuring system lies close to the frequency of any of the sine wave components of the arterial waveform, then the system will resonate, causing excessive amplification, and distortion of the signal. So , it is important that the IABP system has a very high natural frequency – at least eight times the fundamental frequency of the arterial waveform (the pulse rate). Therefore, for a system to remain accurate at heart rates of up to 180bpm, its natural frequency must be at least: (180bpm x 8) / 60secs = 24Hz.

65. The natural frequency of a system is determined by the properties of its components. It may be increased by: - Reducing the length of the cannula or tubing - Reducing the compliance of the cannula or diaphragm - Reducing the density of the fluid used in the tubing - Increasing the diameter of the cannula or tubing

66. Most commercially available systems have a natural frequency of around 200Hz but this is reduced by the addition of three-way taps, bubbles, clots and additional lengths of tubing

67. Damping Coefficient : The amount of damping inherent in a system can be described by the damping coefficient (D) which usually lies between 0 and 1 Critical-Damping Over-Damping Under-Damping Optimal Damping

68. DAMPING Anything that reduces energy in an oscillating system will reduce the amplitude of the oscillations. Some degree of damping is required in all systems ( critical damping ), but if excessive (overdamping) or insufficient (underdamping) the output will be adversely effected. In an IABP measuring system, most damping is from friction in the fluid pathway

69. OVER DAMPING FACTORS Three way taps Bubbles and clots Vasospasm Narrow , long or compliant tubing Kinks in the cannula or tubing Damping also causes a reduction in the natural frequency of the system, allowing resonance and distortion of the signal.

70. Underdamped arterial pressure waveform \ 80 Overdamped arterial pressure waveform

71. FAST-FLUSH TEST Provides a convenient bedside method for determining dynamic response of the system Natural frequency is inversely proportional to the time between adjacent oscillation peaks The damping coefficient can be calculated mathematically, but it is usually determined graphically from the amplitude ratio 81

72. Performed by opening the valve of continuous flush device such that flow through catheter- tubing system is acutely increased to 30ml/ hr from usual 1-3ml/ hr. This generates an acute rise in pressure within the system such that a square wave is generated on bedside monitor. With closure of valve, a sinusoidal pressure wave of a given frequency and progressively decreasing amplitude is generated. A system with appropriate dynamic response characteristics will return to the baseline pressure waveform within one to two oscillations.

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74. Determining natural frequency ( Fn ): Fn = Paper speed (mm/sec)/ wavelength Eg . Paper speed = 25 mm/ sec; wavelength = 1mm Fn = 25/1 = 25Hz

75. When to perform FAST FLUSH TEST Whenever the waveform seems overdamped or underdamped. Whenever physiological changes of the patient ( increased heart rate, vasoconstriction) place higher demand on the monitoring system. After opening the system Before implementing interventions or changes of interventions. Whenever the accuracy of arterial blood pressure measurement is in doubt. At least every 8-12 hours

76. Alternative Arterial Pressure Monitoring Sites 26-07-2016 Dr. Vikram Naidu 88 Ulnar Brachial Axillary Femoral – seldinger technique Dorsalis pedis

77. Percutaneous Radial Artery Cannulation 26-07-2016 Dr. Vikram Naidu 89 The radial artery is the most common site for invasive blood pressure monitoring because it is technically easy to cannulate and complications are uncommon Modified Allen’s test

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79. “Transfixation” technique 26-07-2016 Dr. Vikram Naidu 91

80. Invasive Blood Pressure Monitoring Pulse Contour Analysis : Aortic Stenosis : Pulsus parvus (narrow pulse pressure) Pulsus tardus (delayed upstroke)

81. Aortic regurgitation : Bisferiens pulse (double peak) Wide pulse pressure

82. Hypertrophic cardiomyopathy : Spike-and-dome pattern (midsystolic obstruction)

83. Systolic left ventricular failure : Pulsus alternans (alternating pulse pressure amplitude)

84. Cardiac tamponade : Pulsus paradoxus (exaggerated decrease in systolic blood pressure during spontaneous inspiration)

85. Arterial Pressure Monitoring for Prediction of Volume Responsiveness : systolic pressure variation (SPV)

86. Invasive Blood Pressure Monitoring Pulse Pressure Variation ( PPV )